 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.menus;

 import org.eclipse.jface.util.Util;

 /**
  * <p>
  * An ordering for a location. This is the sort order with respect to other menu
  * elements.
  * </p>
  * <p>
  * Additional position constants may be added in the future.
  * </p>
  * <p>
  * Clients may instantiate this class, but must not extend.
  * </p>
  * <p>
  * <strong>PROVISIONAL</strong>. This class or interface has been added as
  * part of a work in progress. There is a guarantee neither that this API will
  * work nor that it will remain the same. Please do not use this API without
  * consulting with the Platform/UI team.
  * </p>
  * <p>
  * This class will eventually exist in <code>org.eclipse.jface.menus</code>.
  * </p>
  *
  * @since 3.2
  */
 public final class SOrder {

     /**
      * The constant to use if there is no position. This is useful for some
      * algorithms involved collections of ordering constraints.
      */
     static final int NO_POSITION = -1;

     /**
      * The constant to use if the position for the location is the start of the
      * current <code>IMenuCollection</code>.
      */
     public static final int POSITION_START = 0;

     /**
      * The constant to use if the position for the location is the end of the
      * current <code>IMenuCollection</code>.
      */
     public static final int POSITION_END = 1;

     /**
      * The constant to use if the position for the location is to be before a
      * menu element with a particular identifier.
      */
     public static final int POSITION_BEFORE = 2;

     /**
      * The constant to use if the position for the location is to be after a
      * menu element with a particular identifier.
      */
     public static final int POSITION_AFTER = 3;

     /**
      * The position the menu element should be given relative to other menu
      * elements. This should be one of the position constants given by this
      * class.
      */
     private final int position;

     /**
      * The identifier of the menu element to which the position is relative.
      * This value is <code>null</code> iff the position is not a relative
      * position.
      */
     private final String relativeTo;

     /**
      * Constructs a new instance of <code>SOrder</code>. This ordering
      * constraint can be either indicate the start or end. For relative
      * positioning, use {@link SOrder#SOrder(int, String)}.
      *
      * @param position
      * The position in which the menu element should appear with
      * respect to other menu elements. This value should be one of
      * the position constants defined in this class.
      *
      * @see SOrder#POSITION_END
      * @see SOrder#POSITION_START
      */
     public SOrder(final int position) {
         this(position, null);
     }

     /**
      * Constructs a new instance of <code>SOrder</code>.
      *
      * @param position
      * The position in which the menu element should appear with
      * respect to other menu elements. This value should be one of
      * the position constants defined in this class.
      * @param relativeTo
      * The identifier of the menu element to which the position is
      * relative. This value is required if the position is
      * <code>POSITION_AFTER</code> or <code>POSITION_BEFORE</code>.
      * Otherwise, this value should be <code>null</code>.
      *
      * @see SOrder#POSITION_AFTER
      * @see SOrder#POSITION_BEFORE
      * @see SOrder#POSITION_END
      * @see SOrder#POSITION_START
      */
     public SOrder(final int position, final String relativeTo) {
         if ((position < POSITION_START) || (position > POSITION_AFTER)) {
             throw new IllegalArgumentException (
                     "A location needs a valid position. Got: " + position); //$NON-NLS-1$
 }

         if ((position == POSITION_AFTER) || (position == POSITION_BEFORE)) {
             if (relativeTo == null) {
                 throw new NullPointerException (
                         "A location positioned before or after needs an identifier of the menu element to which the position is relative"); //$NON-NLS-1$
 }
         } else if (relativeTo != null) {
             throw new IllegalArgumentException (
                     "A relative identifier was provided for a non-relative position"); //$NON-NLS-1$
 }

         this.position = position;
         this.relativeTo = relativeTo;
     }

     /**
      * Returns the position for this location. The position will be one of the
      * the position constants defined in this class. Additional position
      * constants may be added in the future.
      *
      * @return The position.
      */
     public final int getPosition() {
         return position;
     }

     /**
      * Returns the identifier of the menu element to which this location is
      * relative. There will only be such an identifier if the position is a
      * relative positioning.
      *
      * @return The relative identifier. If the position is not relative, then
      * <code>null</code>.
      * @see SOrder#POSITION_AFTER
      * @see SOrder#POSITION_BEFORE
      */
     public final String getRelativeTo() {
         return relativeTo;
     }

     public final String toString() {
         final StringBuffer buffer = new StringBuffer ();
         buffer.append("SOrder("); //$NON-NLS-1$
 switch (position) {
         case POSITION_AFTER:
             buffer.append("after"); //$NON-NLS-1$
 break;
         case POSITION_BEFORE:
             buffer.append("before"); //$NON-NLS-1$
 break;
         case POSITION_END:
             buffer.append("end"); //$NON-NLS-1$
 break;
         case POSITION_START:
             buffer.append("start"); //$NON-NLS-1$
 break;
         default:
             buffer.append("unknown"); //$NON-NLS-1$
 }
         buffer.append(',');
         buffer.append(relativeTo);
         buffer.append(')');
         return buffer.toString();
     }

     /* (non-Javadoc)
      * @see java.lang.Object#equals(java.lang.Object)
      */
     public boolean equals(Object obj) {
         if (this == obj) {
             return true;
         }
         if (obj instanceof SOrder) {
             SOrder order = (SOrder) obj;
             return position == order.position
                     && Util.equals(relativeTo, order.relativeTo);
         }
         return false;
     }

     /* (non-Javadoc)
      * @see java.lang.Object#hashCode()
      */
     public int hashCode() {
         return position + Util.hashCode(relativeTo);
     }
 }

